I've watched all the films but Monkey Business (I'm saving it for later in the week)... I had seen Horse Feathers and some of Duck Soup on Turner Classic Movies before. These two are some of the funniest films I've seen. The Cocoanuts and Animal Crackers aren't as flawless, but they're stil...
While only Duck Soup was mentioned as a restored version in some article, it's possible Universal did the same for the other 4 films. However, restoration can only do so much if a movie has poor surviving material... For example, the restored version of Sunrise still has lots of print...
Universal DID restore Duck Soup to make a new restoration negative... But keep in mind that a lot of the Paramount films in Universal's ownership have lousy materials to work from. Some lack the original negative and even the original fine-grain positives. Universal's best materials for some...